Large-scale measured body weight changes effect on yield, health, reproduction, and feed efficiency in 3 different dairy cattle breeds

Daily BW predictions from a 3-dimensional camera system were<br/>recorded for Holstein, Jersey and Red Dairy Cattle after each milking.<br/>While individual BW measurements provide limited insights on their<br/>own, the continuous tracking of BW enables the assessment of BW<br/>changes during specific lactation periods, which are of critical importance. this study aimed to explore how BW changes in early and late<br/>lactation, the dry period, and days from calving until lowest weight after<br/>calving affected a cow’s performance for various production traits (e.g.,<br/>yield, reproduction, health, and feed efficiency). Data were available<br/>for a total of 9,142 cows in 19 herds: Jersey (2,513 cows), Red Dairy<br/>cattle (2,813 cows) and Holstein (3,816 cows). Mean BW was higher<br/>for Red Dairy Cattle (647.9 kg) and Holstein (683.8 kg) than Jersey<br/>(469.6 kg). Body weight changes were significantly related to various<br/>production traits. The analysis showed unfavorable effect of reduced<br/>BW in the dry period compared with lactation yield in the following<br/>lactation. Notably, cows that lost 25 kg during the dry period produced<br/>up to 8% less milk in the subsequent lactation compared with cows<br/>sustaining BW levels in the dry period (P &lt; 0.05). Moreover, there is a<br/>positive effect on reproduction success as first inseminations of cows<br/>if performed in positive energy balance used 0.2 inseminations less per<br/>pregnancy compared with negative energy balance (P &lt; 0.05). Body<br/>weight gain in late lactation was significantly related to BW loss in the<br/>dry period as well as to higher frequency of ketosis in the following<br/>lactation (P &lt; 0.05). In general, the effects where similar across breeds<br/>both for the weight changes during lactation but also for the effects of<br/>weight changes on production traits. Weight loss in early lactation in<br/>percent of BW though was smaller for Red Dairy Cattle than for Holstein<br/>and Jersey. Also, the effect of weight change in late lactation effected<br/>feed intake in early lactation in the following lactation. For many traits<br/>there are substantial herd effects indicating both different management<br/>protocols but also different strategies and goals. This can and will lead<br/>to local truths, leading to improved management.